/*
   * Cryptographic API for the 842 compression algorithm.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   *
   * Copyright (C) IBM Corporation, 2011
   *
   * Authors: Robert Jennings <rcj@linux.vnet.ibm.com>
   *          Seth Jennings <sjenning@linux.vnet.ibm.com>
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/crypto.h>
  #include <linux/vmalloc.h>
  #include <linux/nx842.h>
  #include <linux/lzo.h>
  #include <linux/timer.h>
  
  static int nx842_uselzo;
  
  struct nx842_ctx {
  	void *nx842_wmem; /* working memory for 842/lzo */
  };
  
  enum nx842_crypto_type {
  	NX842_CRYPTO_TYPE_842,
  	NX842_CRYPTO_TYPE_LZO
  };
  
  #define NX842_SENTINEL 0xdeadbeef
  
  struct nx842_crypto_header {
  	unsigned int sentinel; /* debug */
  	enum nx842_crypto_type type;
  };
  
  static int nx842_init(struct crypto_tfm *tfm)
  {
  	struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
  	int wmemsize;
  
  	wmemsize = max_t(int, nx842_get_workmem_size(), LZO1X_MEM_COMPRESS);
  	ctx->nx842_wmem = kmalloc(wmemsize, GFP_NOFS);
  	if (!ctx->nx842_wmem)
  		return -ENOMEM;
  
  	return 0;
  }
  
  static void nx842_exit(struct crypto_tfm *tfm)
  {
  	struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	kfree(ctx->nx842_wmem);
  }
  
  static void nx842_reset_uselzo(unsigned long data)
  {
  	nx842_uselzo = 0;
  }
  
  static DEFINE_TIMER(failover_timer, nx842_reset_uselzo, 0, 0);
  
  static int nx842_crypto_compress(struct crypto_tfm *tfm, const u8 *src,
  			    unsigned int slen, u8 *dst, unsigned int *dlen)
  {
  	struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct nx842_crypto_header *hdr;
  	unsigned int tmp_len = *dlen;
  	size_t lzodlen; /* needed for lzo */
  	int err;
  
  	*dlen = 0;
  	hdr = (struct nx842_crypto_header *)dst;
  	hdr->sentinel = NX842_SENTINEL; /* debug */
  	dst += sizeof(struct nx842_crypto_header);
  	tmp_len -= sizeof(struct nx842_crypto_header);
  	lzodlen = tmp_len;
  
  	if (likely(!nx842_uselzo)) {
  		err = nx842_compress(src, slen, dst, &tmp_len, ctx->nx842_wmem);
  
  		if (likely(!err)) {
  			hdr->type = NX842_CRYPTO_TYPE_842;
  			*dlen = tmp_len + sizeof(struct nx842_crypto_header);
  			return 0;
  		}
  
  		/* hardware failed */
  		nx842_uselzo = 1;
  
  		/* set timer to check for hardware again in 1 second */
  		mod_timer(&failover_timer, jiffies + msecs_to_jiffies(1000));
  	}
  
  	/* no hardware, use lzo */
  	err = lzo1x_1_compress(src, slen, dst, &lzodlen, ctx->nx842_wmem);
  	if (err != LZO_E_OK)
  		return -EINVAL;
  
  	hdr->type = NX842_CRYPTO_TYPE_LZO;
  	*dlen = lzodlen + sizeof(struct nx842_crypto_header);
  	return 0;
  }
  
  static int nx842_crypto_decompress(struct crypto_tfm *tfm, const u8 *src,
  			      unsigned int slen, u8 *dst, unsigned int *dlen)
  {
  	struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct nx842_crypto_header *hdr;
  	unsigned int tmp_len = *dlen;
  	size_t lzodlen; /* needed for lzo */
  	int err;
  
  	*dlen = 0;
  	hdr = (struct nx842_crypto_header *)src;
  
  	if (unlikely(hdr->sentinel != NX842_SENTINEL))
  		return -EINVAL;
  
  	src += sizeof(struct nx842_crypto_header);
  	slen -= sizeof(struct nx842_crypto_header);
  
  	if (likely(hdr->type == NX842_CRYPTO_TYPE_842)) {
  		err = nx842_decompress(src, slen, dst, &tmp_len,
  			ctx->nx842_wmem);
  		if (err)
  			return -EINVAL;
  		*dlen = tmp_len;
  	} else if (hdr->type == NX842_CRYPTO_TYPE_LZO) {
  		lzodlen = tmp_len;
  		err = lzo1x_decompress_safe(src, slen, dst, &lzodlen);
  		if (err != LZO_E_OK)
  			return -EINVAL;
  		*dlen = lzodlen;
  	} else
  		return -EINVAL;
  
  	return 0;
  }
  
  static struct crypto_alg alg = {
  	.cra_name		= "842",
  	.cra_flags		= CRYPTO_ALG_TYPE_COMPRESS,
  	.cra_ctxsize		= sizeof(struct nx842_ctx),
  	.cra_module		= THIS_MODULE,
  	.cra_init		= nx842_init,
  	.cra_exit		= nx842_exit,
  	.cra_u			= { .compress = {
  	.coa_compress		= nx842_crypto_compress,
  	.coa_decompress		= nx842_crypto_decompress } }
  };
  
  static int __init nx842_mod_init(void)
  {
  	del_timer(&failover_timer);
  	return crypto_register_alg(&alg);
  }
  
  static void __exit nx842_mod_exit(void)
  {
  	crypto_unregister_alg(&alg);
  }
  
  module_init(nx842_mod_init);
  module_exit(nx842_mod_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("842 Compression Algorithm");